The present invention is directed to a device and method for installing an oil seal to a crankshaft. More particularly, the present invention is directed to a device and method for installing an oil seal to the output end of an internal combustion engine crankshaft. The device and method of the present invention is primarily intended for use in a high-volume production setting, but could also be used in repair shops or similar environments.
Internal combustion engines have existed in some form for approximately 200 years. Such engines may take many forms. For example, internal combustion engines may be of the diesel, rotary, gas turbine, two-stroke, or four-stroke variety. Four-stroke internal combustion engines are likely the most common, and serve as the powerplant in the vast majority of today's automobiles. Two-stroke engines can still be found in some motorcycles and in various types of outdoor power equipment. Diesel engines are typically used to power trucks and other heavy equipment, and are also used in a smaller percentage of automobiles. Gas turbine engines are generally used to power aircraft, such as jet aircraft and helicopters, and can also be used to power electric generators and other rotationally-driven devices.
While the overall operation of these aforementioned internal combustion engines may vary considerably, they all have one thing in common: the power generated by each engine is delivered via some form of shaft. In the four-stroke internal combustion engine, for example, engine power is commonly delivered to a drive system by means of a crankshaft. The crankshaft is typically connected by one or more connecting rods to a like number of pistons that reciprocate within respective cylinder bores in an engine block. A mixture of fuel and air is admitted into the cylinder bore(s) in an area above each piston, where it is ignited and exploded. The explosion of fuel causes reciprocation of the piston(s), and a resulting rotation of the crankshaft. The crankshaft rotates within the engine block, where it may be supported by a number of bearings. A lubricant, such as motor oil, is normally provided within the engine block to facilitate rotation and cooling of the crankshaft and related components.
In order to transfer engine power to an external mechanism, such as the wheels of an automobile, at least one end of the crankshaft must typically protrude through the engine block (or must be accessible through the engine block). In an automobile, for example, at least one end of the crankshaft is usually coupled to a manually or automatically shifted transmission. As can be understood from the foregoing description of such an engine, however, extending the crankshaft through the engine block can be problematic due to the presence of motor oil within the engine block. More specifically, the opening between the engine block and the crankshaft invites oil leaks and, therefore, must be sealed. With respect to an automobile engine, this seal is often referred to as the rear main bearing oil seal, or the rear main seal.
Sealing the gap between the crankshaft and the engine block has been a problem since the early days of internal combustion engine usage. Prior to the development of suitable rubber and polymer materials, sealing was typically accomplished by inserting a piece of specialized rope between the crankshaft and the surrounding aperture in the engine block. The size of the rope was selected to fit tightly therebetween. Early rubber and polymer seal designs typically mimicked the earlier rope seals, in that they commonly took the shape of long strands or bands that were pulled around the circumference of the crankshaft in the area to be sealed, and then were subsequently cut to proper length.
Modern oil seals are much more advanced in design, and offer far superior sealing abilities and a longer service life. Today's crankshaft oil seals generally employ a polymer material, and may incorporate a metal support wire or may be joined to a metallic ring that gets pressed into a receiving aperture in the engine block. A metallic ring may be present along the outer diameter of the seal, the inner diameter of the seal, or both.
While such seals are generally superior in both their sealing abilities and service life, they must be properly installed in order to produce the desired effect. More specifically, when an oil seal includes an outer metallic ring, there will generally be some resistance to insertion thereof by the receiving aperture in the engine block. This resistance allows the oil seal to be adequately retained within the aperture. If proper measures are not taken during installation, however, it is possible for the resistance between the oil seal and the aperture to cause installation of the oil seal in an angled or “cocked” position—which can detrimentally affect the sealing abilities of the oil seal. It is also sometimes possible, depending on the design of the oil seal and the aperture in the engine block, to install the oil seal to an incorrect depth (i.e., too far into the aperture).
Various tools and techniques have in the past been used to assist in properly installing this type of oil seal, including the technique of spanning the oil seal with a board and striking the board with a hammer to drive the oil seal into the aperture. A number of hand operated tools that must be physically fastened to the end of the crankshaft prior to use have also been developed for this purpose.
While these known tools and installation techniques may work acceptably for a one-time installation, or for low volume oil seal installation such as in a typical repair facility, they are not acceptable in a high volume manufacturing setting. For example, quality issues aside, it is not practical to use the board and hammer installation method on an automotive assembly line. Similarly, while some of the hand operated tools mentioned above may improve the resulting quality of the oil seal installation process, there is simply not enough time in a manufacturing setting to fasten and unfasten a tool to the end of the crankshaft during each oil seal installation operation.
Therefore, what is needed, and to Applicants' knowledge has been heretofore unavailable, is an oil seal installation device that not only ensures the proper installation of the oil seal, but also performs the installation with an efficiency that allows its use in a high volume manufacturing environment. The crankshaft oil seal installation device of the present invention satisfies this need.